Method and apparatus for freezing perishable material



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)Wa/w02 .9e/so BY PARA/1? 6402A Arron/vers United States Patent 3,022,637 METHOD AND APPARATUS FR FREEZING PERISHABLE MATERIAL Willard L. Morrison, Lake Forest, lll., assignor to Liquefreeze Company, Inc., New York, NY., a corporation of New York Filed Aug. 22, 1960, Ser. No. 24,068 6 Claims. (CI. 62-64) My invention is especially applicable to the freezing or superchilling of foodstuffs and the like which are packed and shipped in insulated shipper containers. I have illustrated my invention as applied to a truck trailer body though it might be equally well applied to a freight car, a ship or an airplane.

The material to be superchilled is normally frozen down to a temperature in the order of zero degree F., the small paper packages or cans being packed, quite a number of them in rectangular, rough paper or corrugated board cartons. These cartons are then packed in and substantially till the insulated container. The container is closed and liquid nitrogen in the order of 320 degrees F. and at atmospheric pressure is poured or flowed into `the container so that it may drench the surfaces of the cartons, penetrate in the cartons as a liquid, be absorbed by and pass through the carton walls and contact the contents of the carton so as to reduce the temperature of the carton contents down to a desired low temperature far below zero degree F.

The cartons are packed closely together as they must in order to take best advantage of the insulated container and in order to prevent damage in transit but being packed closely together, they inhibit convection currents and to some extent retard liquid and gas iiow along the boundaries of the mass and along boundary walls between the cartons. Hence the very great irnportance of insuring that the liquid nitrogen flows as liquid and contacts as liquid the cartons and their contents because liquid Will flow through said spaces more readily.

The liquid as -it contacts the warm cartons and their contents, boils, is evaporated and expands some six hundred times, thus cooling the contents of the container largely by latent heat, the gas rushing violently away from the area of contact.

It is important to be able to diiferentially control the temperature to which diierent parts of the cargo are cooled. Perhaps part of the cargo goes to a further destination than other parts. Perhaps diierent parts of the cargo are destined for storage under different circumstances and of course the top of the cargo being exposed to the heat of the sun on the roof of the container needs to be cooler to start with than the remainder of the cargo and if the direction of travel is known as it always is, one side of the container may be more exposed to sun than the other so that for all these reasons, some means of controlling and directing the flow of liquid to specic points as desired must be provided.

This is accomplished by having at the top of the container a grid of pipes permanently established there, the pipes being apertured along their lengths, the apertures being of substantial size, preferably laterally directed. The grid will be associated with an outside manifold built into the container through which the liquid may be caused to ow and various parts of the grid may be separately valve controlled so as to direct the ow of liquid into a desired part or parts of the container.

Since the liquid expands six hundred times, the velocity of gas escape from the container is quite high and exhaust ports for the gas must be provided many times in cross sectional area than the cross sectional area of the pipe. Such exhaust ports are provided in both Walls ice of the container, there being a large number of them in each wall, the total area of the gas ports being substantially larger than necessary to accommodate the ow of gas evaporated from the liquid. Each of these ports is provided with a separate closure. When it is desired to cool a particular part of the load, the Valve or valves controlling the liquid iiow to that area are open and the exhaust ports adjacent that area are open. Then as the evaporation takes place, the gas rushes rapidly toward the open exhaust ports, entraining with it the liquid as it continues to pour out into the container. Thus the direction of ow of the liquid as it cools the contents of the container is controlled by the control or rather by the location at which the gas is allowed to escape.

Thus the liquid is entrained and directed to a desired point merely by controlling the gas vent openings.

Other objects will appear from time to time throughout the specilication and claims.

The invention is illustrated more or less diagrammatically in the accompanying drawings, wherein- FIGURE l is a side elevation of a shipper container;

FlGURE 2 is a section along the line 2 2 of FIG. URE l;

FIGURE 3 is a section along the line 3 3 of FIG- URE l;

FiGURE 4 is a section along the line 4 4 of FIG- RE l;

FIGURE 5 is a side elevation of a part of FIGURE 4 taken in the direction of the arrows 5 5;

FIGURE 6 is a section along the line 6 6 of FIG- URE 3;

FIGURE 7 is a section along the line 7 7 of FIG- URE 6;

FIGURE 8 is .la side elevation of an insulating plug used to fill vents in the container;

FIGURE 9 is an exploded section of a different type of vent plug for use in connection with the ller openings;

FIGURE l0 is a side elevation of the device shown in FIGURE l showing some of the ducts plugged and others open;

FIGURE ll is a section along the line 11-11 of FIGURE l0 showing at least one sealing duct open;

FIGURE l2 is a section along the line 12-12 of FIGURE l0.

Like parts are indicated by 4like numerals throughout the specification and drawings.

The shipper container shown in side elevation in FIG- URE 1 is illustrated as an insulated truck trailer having side walls i, front wall 2, rear end door 3 and roof 4. he contents of the container are not illustrated in the interest of clarity but it must be understood that the cartons or other containers are packed as closely as possible to ll the container. Extending across the container at the top are two manifolds 5, 6. There might be more or one could be used. Extending longitudinally from these manifolds along the top of the container are grid pipes 7, 8, 9 and l@ which may, if desired, terminate in cross pipes 11. The manifolds, the grid pipes and the cross pipes 11 are all perforate as at 12. The perforations l2 discharge either horizontally or diagonally upwardly and are so positioned that they cannot be masked by the load in the car. The purpose is that as the liquid jets through these perforations, it will be discharged in part horizontally and in part upwardly to impinge on the underside of the car roof and be deflected diagonally downwardly along the loading. Valves 14 with operating hand wheels 15 outside the container may be manipulated to open or close as desired one or al1 of the pipes 7, S, 9 and 10.

Ports 16 are spaced along the upper and lower portions of the walls 1. The spacing may be close or far apart as desired, the spacing or arrangement being a matter of preference except that there must be ports adjacent the top and adjacent the bottom of the load.

Each of these ports communicates with the interior of the container by a downwardly inclined duct 17 Vertical ports 17a are disposed in the roof of the car being closed by similar plugs 19, flanged at 20. The upper boundary of the duct at its inner end being far below the lower boundary of the port 16. Each of these ports at the inboard end is masked by a cross bar 18 and each of these ducts may be closed by an insulating plug 19, flanged at 20 which may be locked in place, if desired.

The reason for having the apertures 12 above the lowest boundary of the pipes is to make sure that no matter how tightly packed the packages are, the package wall will not close the aperture so that liquid may ow out of that aperture as a liquid without any atomization or without any substantial increase in pressure so that the liquid may be entrained by the gas as it rushes toward the selectively opened gas ports.

The reason for the bars 18 is the same. It insures that no matter how closely the cartons are packed, they will not mask the exhaust ducts 17.

The drip pan 22 at the bottom of the container is masked by a flange 21 so that any liquid as it pours down will be caught and retained long enough for evaporation without saturating the lower portion of the insulation. Insulation of this type being tight enough to normally inhibit gas flow but not enough to be liquid tight.

The use and operation of the invention are as follows:

Assuming for example that it is desired to especially cool that part of the load immediately below the longitudinal pipe 7, valve 14 in connection with the pipe 8 will be closed. A sealing plug will be taken out of one end of the manifold 5, the sealing plug remaining in the other end. A hose will be inserted in the manifold to replace the plug and the hose can well be screwed into place to make a tight joint. The sealing plugs on some or all of the ports on the side of the vehicle nearest the pipe 7 will be open, all the other plugs remaining closed. Liquid nitrogen will ow in, pouring as liquid out upon the upper portion of the load. As it evaporates the gas violently seeks an outlet. It rushes out at high velocity through the container past the load and out through the open port. Traveling at high velocity, it tends to entrain the liquid, thus increasing and spreading the cooling eect, the liquid evaporating as it is entrained. The more liquid that goes in, the colder the packages, the further the liquid can go before it evaporates until nally you might get a situation where the liquid gets clear down to the port. Under those circumstances the liquid will be deflected, will not flow upwardly through the exhaust ducts.

When the proper degree of cold has been reached which may be determined by any suitable means, liquid flow will be stopped and other parts of the package may be irrigated with the liquid nitrogen.

It is of the utmost importance that the liquid flow onto the goods as liquid, not as a spray because if the nitrogen is sprayed, it Vaporizes before it reaches the goods and heat exchange with a vapor, or gas is much less eifective and much more wasteful than heat exchange with a liquid.

Under some circumstances, frost may accummulate in the ducts 17 but because the ducts are downwardly inclined and because the bar 18 is tangent to the upper wall of the duct, frost may be knocked out by pushing a rod through the port 16 and along the duct 17. The duct 17 being downwardly inclined serves as a baille so that horizontally flowing liquid will not under ordinary circumstances escape through the port 16 and since the ducts are all upwardly inclined and much of the gas comes from above, there will be a sudden change of direction, thus separating out the liquid from the gas by centrifugal force.

I have used the term Kapproximately or substantially atmospheric in connection with the nitrogen and the gas. By this I mean that the pressure in the container in the car is not great enough to substantially affect the temperature of evaporation or boiling is not great enough sto put any substantial load on the structure. The pressure on the liquid nitrogen as it ows into the car is, of course, sufficient. There may be a pressure equal to the pressure of an inch or so of Water to cause it to flow into the car. The pressure in the car may be a few more inches of water resulting from the evaporation of the gas is great enough to insure violent discharge of the gas from the car at a rate suflicient, as `the gas travels through the car to entrain the liquid, thus moistening the selected area between liquid supply land gas discharge to insure a cooling of the contents.

The apertures in the pipes are as indicated generally horizontal or perhaps upwardly inclined. What is desired is the liquid as it ilows will be discharged laterally along the surface of the load. The load, of course, cannot be put in above the pipes. Perhaps some of the liquid may impinge on the ceiling of fthe car and rain down and as soon as the surface is at the temperature of the liquid, no further vaporization at that point will occur. Thus there is a tendency toward distribution of the liquid on the surface of the load so that the liquid may spray out and with the help of the injection or entrainment action of the gas cover the Whole upper surface of the load and be able thereafter to ow down along the outside boundaries of the load toward the bottom of the load in a bath of liquid trapped in the bottom of the car, thus differentially cooling top, side and bottom of the load.

Since each manifold extends clear yacross the car and may be opened at either end, it is necessary to close one end when liquid is to be supplied through the other end. This is done by means of a screw plug 30 threaded in the end of the manifold at 31 and this screw plug may be insulated and masked by an insulating plug 32. There will never be more than one end of the manifold open and after the freeze down, both ends of the manifold Will be closed.

The ports in the door of the container may be opened or closed depending on the direction of flow of liquid and gas desired. In FIGURES l0 and l2, I have illustrated some of the lower ports 16 as being open so that gas will rush out at that point entraining the liquid toward it from the source of liquid supply. In FIGURE ll, I have shown a port in the top of the container open so that gas may rush out at that point.

I claim:

l. The method of chilling perishable material, which consists in filling a closable insulating zone with a multiplicity of packages of the material, pouring liquid nitrogen into the zone at substantially atmospheric pressure, for contact with and boiling by the heat of the contents of the zone, conveying the liquid in the Zone to a selected portion thereof by inducing the high velocity flow of the resultant gas from the area Where boiling occurs toward one of a plurality of selected gas discharge points.

2. The method of chilling perishable material, which consists in filling a closable insulating zone with a multiplicity of packages of the material, pouring liquid nitrogen into the zone at substantially atmospheric pressure in contact with and boiling by the heat of the contents of the zone, discharging the resultan-t gas at high velocity from the Zone at one of a plurality of selected points far removed from the area Where the boiling occurs, the Velocity of the gas as it flows from the point Where boiling occurs to the point of discharge being such that liquid is entrained by the gas toward the point of discharge.

3. Means for chilling perishable material including a closable insulated container in which a multiplicity of relatively warm packages of the material may, before closing, be packed, means for discharging liquid nitrogen at atmospheric pressure into the container into contact with the Warm packages at any one or more of a plurality of selected locations whereby the liquid is vaporized for discharging the resultant gas from the container at any one or more of a plurality of selected locations.

4. Means for chilling perishable material including a closable insulated container in which a multiplicity of relatively warm packages of the material may, before closing, be packed, a liquid pipe supply system Within the container, a plurality of liquid supply pipes adapted to discharge liquid nitrogen at atmospheric pressure into the container, valve means controlling ow through said pipes, a plurality of gas discharge ports extending through the wall of the container and means for opening and closing selected ports.

5. Means for chilling perishable material including a closable insulated container in which a multiplicity of relatively Warm packages of the material may, before closing, be packed, means for discharging liquid nitrogen at atmospheric pressure into the container in contact with the Warm packages at a selected station, means for discharging vthe resultant gas from the container at a selected station far removed from the point of supply.

6. Means for chilling perishable material including a closable insulated container in which a multiplicity of relatively Warm packages of the material may, before closing, be packed, means for discharging liquid nitrogen at yatmospheric pressure into the container in Contact with the warm packages at a selected station, means for discharging the resultant gas from the container at a selected station far removed from the point of supply, said means including a multiplicity of gas discharge ports in the container and means for selectively opening and closing them.

References Cited in the tile of this patent FOREIGN PATENTS 1,166,555 France June 23, 1958 

